feat: HLS streaming, transcripts, agent course generation & landing-page course previews (#663)

New features:
- HLS video encoding/streaming (hls routes, hls-encoder) and a media
  transcripts pipeline (transcripts route + media-transcript queries)
- AI assistant chat vs. run model: agent-course-generation worker/queue,
  run-monitor pane, chat-changes card, content ask-ai bar
- Per-theme course-page previews across org landing-page themes (bold,
  classic, corporate, editorial, etc.) with a shared course token/component set
- View-as-student mode and login-link / link-invite invite flows

Refactor:
- Extract packages/core consolidating config (env, storage, dashboard-url),
  services and utils previously duplicated under apps/api/src/config
- Remove legacy agent service modules (chat-tools, chat-context,
  context-window, document, fetch-url, lesson-content)
- Relax Cross-Origin-Resource-Policy to allow cross-origin media embedding
- Add format script to tenant-router so turbo run format covers it

apps/dashboard/vite.config.ts

@@ -17,12 +17,21 @@ export default ({ mode }) => {
     plugins: [sveltekit()],
     server: {
       ...getServer(process.env),
+      fs: {
+        // `..` is `apps/` — covers the dashboard's own files. `../../packages`
+        // is required so Vite's `@fs` route can serve dynamic imports that
+        // workspace packages (e.g. `@cio/ui/custom/editor`) emit as absolute
+        // paths into their own source tree. Without it, dev 403s on those
+        // `@fs/.../packages/ui/...` URLs.
+        allow: ['..', '../../packages']
+      },
       watch: {
         ignored: ['**/node_modules/!(@cio)/**', '**/.git/**']
       }
     },
     build: {
-      sourcemap: false
+      sourcemap: true,
+      target: 'es2020'
     },
     ssr: {
       // svelte-motion uses directory imports without `/index.js`; Node ESM fails unless bundled for SSR.